Stylized procedural modeling for 3d navigation

ABSTRACT

A method of displaying a navigation map includes determining a route of a vehicle. A two-dimensional footprint of a building disposed within a geographic area is received within the vehicle. The geographic area includes the route of the vehicle. Attribute information associated with the building is received. The attribute information is received within the vehicle. A visual representation of the building is rendered based upon the two-dimensional footprint and the attribute information.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to electronic navigation maps, and, moreparticularly, to rendering images for electronic navigation maps.

2. Description of the Related Art

Navigation maps are essential resources for visitors to an unfamiliarcity because these maps visually highlight landmarks includingbuildings, natural features, and points of interest such as museums,restaurants, parks and shopping districts. While most in-car andportable navigation devices (PNDs) rely on two-dimensional (2D)navigation maps to visualize these landmarks in 2D, three-dimensional(3D) in-car navigation systems are emerging.

Using a 3D map for navigation can provide a lot of benefits. Forexample, a 3D map can provide better driver orientation than a 2D mapbecause people live in a 3D world. A 3D map can also improve landmarkrecognition as the important features (e.g., geometry, structures,textures) of 3D buildings/landmarks can be fully exposed so that it willbe a lot easier for a user to match these features with what he couldsee through the windshield. However, introducing 3D in a navigation mapalso brings in typical 3D occlusion problems, which could negativelyimpact the visibility of route guidance for navigation.

A 3D navigation system allows drivers to locate point of interests(POIs) and set up routes in a 3D environment. However, high geometriccomplexity of scene buildings and the required 3D rendering efforts mayaffect the performance of such systems on embedded platforms. On onehand, complete data of 3D buildings with highly detailed structures arenot yet available everywhere from data providers. In most cases, thesehighly detailed data (e.g., complex geometry, texture) are available foronly a few outstanding landmarks (e.g., museums, tower) in cities orurban areas. The available information for most non-landmark buildingsin these areas may include only some simple geometry information such as2D footprint, the height of the building, and some descriptions forbuilding types. The lack of detailed 3D geometry and building texturespresents a great challenge for visualization in 3D navigation. It ispossible to simply lift up a building from its 2D footprint according tothe height of the building. This 2.5D approach was widely adopted inmost commercial 3D navigation systems, an example of which is shown inFIG. 1. As can be seen in FIG. 1, such a building presentation (i.e.,2.5D lifting, no texture information) does not distinguish buildingswith different types and therefore cannot improve building/landmarkrecognition or 3D orientation for the driver. On the other hand,rendering highly detailed city models may be limited by the available 3Dcomputation resources provided by embedded hardware platforms for cars.In summary, the 2.5D approach can successfully handle the missing dataproblem by presenting city models with low details. However, the cost isthat such a building presentation fails to convey sufficient informationfor navigation.

A photorealistic 3D Map with high details can present a vivid andrealistic scene to drivers, an example of which is shown in FIG. 2.These maps try to faithfully visualize the structure, geometry andtexture of every object in a 3D scene. However, it could be problematicto use such a building presentation for 3D navigation. For example, thispresentation may overwhelm drivers with too many details. In otherwords, it could significantly increase the cognitive load on the userduring driving, distract the driver's attention, and fail to conveyimportant information to the driver.

Previous work on procedural modelling of buildings focuses on creatingan urban environment with a large number of 3D buildings. CGA shape, anovel shape grammar, is used to iteratively produce more geometricdetails from a simple mass model, as described in “Procedural Modelingof Buildings” by P. Mueller, P. Wonka, S. Haegler, A. Ulmer, and L. V.Gool, Proceedings of ACM SIGGRAPH 2006, which is hereby incorporated byreference herein in its entirety. These works aim to generate buildingswith complex structure and rich details. For example, in a typical urbanscene, the number of polygons used in 3D buildings can reach onebillion. However, for navigation applications, these approaches cannotbe used for several reasons. First, the computation cost of themodelling process is too expensive. Generating one 3D building with highcomplexity (e.g., between one thousand and one hundred thousandpolygons) takes about one to three seconds, which may not meet the speedrequirement for on-line modelling for large-scale urban scenes in a 3Dnavigation. Second, the memory footprints for these highly detailed 3Dbuildings are too large for typical embedded platforms which usuallyhave very limited memory capacity. Finally, although the subtle detailsof these 3D building are generated based on architecture principles,they are more likely to deviate a lot from a building's actualappearance. Drivers tend to take these random details as reference andtry to match them with those from actual buildings. Therefore, theserandom and fake details distract users' attention from navigationwithout providing useful guidance. FIG. 5 a illustrates such a buildingwith such random details.

What is neither disclosed nor suggested by the prior art is a method forpresenting 3D landmarks and other 3D objects on a navigation map thatovercomes the problems and disadvantages described above.

SUMMARY OF THE INVENTION

The present invention may provide an on-line procedural modellingapproach to visualize buildings in a large-scale urban scene in astylized way. Based on this approach, 3D buildings can be generatedautomatically and rapidly, even with only the limited buildinginformation provided from data providers. The generated 3D buildingsfeature moderate geometric complexity and illustrative styles, and mayconvey important details of the 3D building to the driver for 3Dnavigation. Furthermore, the stylized 3D presentations of thesebuildings may visualize the buildings' attributes (e.g., building typesuch as hospital, church, railway stations, etc.) for the driver. Thisapproach may use only the 2D footprint and attributes of the 3D buildingas input and perform fast 3D modelling on-line, which may substantiallyreduce the demand for 3D data storage. The approach of the invention mayalso be adaptive. For example, the complexity level of resultant 3Dbuildings may be adjustable in order to achieve better run-timeperformance for different hardware platforms.

To overcome the difficulties of the prior art, the present invention maytake advantage of procedural modelling and adapt it to the navigationdomain. Procedural modelling is described in “Procedural Modeling ofCities” by Y. I. H. Parish and P. Mueller, Proceedings of ACM SIGGRAPH2001, which is hereby incorporated by reference herein in its entirety.The novel procedural modelling approach of the present invention maygenerate stylized buildings in real time. The 3D objects may bevisualized in an illustrative way such that only important informationis conveyed to the driver. This approach is effective and suitable fornavigation purposes. Illustrated in FIGS. 3 and 4 are examples of theresults of the approach of the present invention used in a 3D navigationprototype system.

The invention comprises, in one form thereof, a method of displaying anavigation map including determining a route of a vehicle. Atwo-dimensional footprint of a building disposed within a geographicarea is received within the vehicle. The geographic area includes theroute of the vehicle. Attribute information associated with the buildingis received. The attribute information is received within the vehicle. Avisual representation of the building is rendered based upon thetwo-dimensional footprint and the attribute information.

The invention comprises, in another form thereof, a method of displayinga navigation map including determining a route of a vehicle.Geographical coordinates of a location of the vehicle are received. Ageographic area in which the geographical coordinates are disposed isdetermined. Data associated with buildings that are disposed within thegeographic area is received. The geographic area includes the route ofthe vehicle. The data includes building types and building heights. Eachof the buildings is rendered based upon the geographic area in which thebuilding is disposed, the building's type, the building'sthree-dimensional shape, and the building's height.

The invention comprises, in yet another form thereof, a method ofdisplaying a navigation map including determining a route of a vehicle.A two-dimensional footprint of a building that is disposed within ageographic area is received within the vehicle. The geographic areaincludes the route of the vehicle. The two-dimensional footprint isdecomposed into tractable parts. Geometry information associated withthe building is received within the vehicle. Each of the tractable partsis modeled separately in combination with a respective portion of thegeometry information associated with each of the tractable parts. Avisual representation of the building is rendered based upon acombination of the modelings of each of the tractable parts.

An advantage of the present invention is that the type of building thatis rendered may be easily recognized by the viewer due to the commoncoloring and texturing, and yet the distinctive details of individualbuildings are still preserved in the renderings.

BRIEF DESCRIPTION OF THE DRAWINGS

The above mentioned and other features and objects of this invention,and the manner of attaining them, will become more apparent and theinvention itself will be better understood by reference to the followingdescription of embodiments of the invention taken in conjunction withthe accompanying drawings, wherein:

FIG. 1 is an example of a 2.5D presentation for non-landmark buildingsin a 3D navigation system of the prior art.

FIG. 2 is an example of a photorealistic 3D map according to the priorart.

FIG. 3 is one example of an NPR 3D map rendering in which a stylizedprocedural modeling approach of the present invention is used togenerate non-landmark building for a 3D navigation prototype system.

FIG. 4 is another example of an NPR 3D map rendering that may beproduced by a method of the present invention in which non-landmarkbuildings are generated with styles different than in the rendering ofFIG. 3.

FIG. 5 a is an example of a building with random details that maydistract a user's attention from navigation.

FIG. 5 b is an example of a stylized building presentation that conveysimportant information about the building, such as building type.

FIG. 5 c is another example of a stylized building presentation with adifferent footprint than in FIG. 5 b, which represents the building'sreal-life footprint.

FIG. 5 d is another example of stylized procedural modeling for aparking garage building.

FIG. 6 a is an example of a building's 2D footprint, which may includeattribute information such as building type.

FIG. 6 b is an example of a decomposition of the footprint of FIG. 6 a.

FIG. 6 c is an example of building geometry consistent with thefootprint of FIG. 6 a.

FIG. 6 d is an example of a stylized 3D building resulting from acombination of all individual 3D components.

FIG. 7 a is an example of adaptive stylized procedural modeling of abuilding according to a method of the present invention.

FIG. 7 b is another example of adaptive stylized procedural modeling ofa building generated from the same 2D footprint as in FIG. 7 a, buthaving a less complicated geometric structure for the roof as comparedto FIG. 7 a.

FIG. 8 is a block diagram of one embodiment of a 3D map renderingarrangement of the present invention.

FIG. 9 is a flow chart of one embodiment of a method of the presentinvention for displaying a navigation map.

FIG. 10 is a flow chart of another embodiment of a method of the presentinvention for displaying a navigation map.

FIG. 11 is a flow chart of yet another embodiment of a method of thepresent invention for displaying a navigation map.

Corresponding reference characters indicate corresponding partsthroughout the several views. Although the exemplification set outherein illustrates embodiments of the invention, in several forms, theembodiments disclosed below are not intended to be exhaustive or to beconstrued as limiting the scope of the invention to the precise formsdisclosed.

DESCRIPTION OF THE PRESENT INVENTION

The invention may provide a method of 3D navigation using NPR 3D maps,including stylized visualization for the 3D objects in a navigation map.The 3D objects displayed on a 3D navigation map may include buildings,landmarks, POIs, hazard spots, and roads. The NPR 3D maps may be createdbased on 3D object data that may be generated in different ways.

According to one embodiment of the method of the present invention, onlya small amount information about 3D buildings (e.g., a building's 2Dfootprint, building height, utility type) may be stored in the storagemedia. For on-line processing, these 3D models may be generated withmoderate geometric complexity and stylized texture decoration in realtime. The generated 3D buildings may have distinguishable styles.Although the buildings may have variations on geometry, the structureand appearance (e.g., texture, color) may be generated consistentlybased on the attributes of buildings. For example, the churches in FIGS.5 b and 5 c have different footprints and roof geometries, but theirappearances (i.e., greenish roof, doors with cross-like decorations) aredesigned to covey the most important information for a church that islocated in a certain area (e.g., Berlin in Germany) to the driver. Inother words, each of these non-landmark buildings is visualized using anenhanced “3D icon” -like approach. The buildings of the same type mayshare the same visual appearance (e.g., color, texture, etc.). However,buildings of the same type may be presented with different 3D shapes andheights, which may also emphasize the important details for eachindividual building for the driver. Moreover, the common appearance ofthe type of buildings may be different in different geographical areas.This may be because the real-life representative style/appearance foreach type of non-landmark buildings could be different in differentgeographical areas (e.g., a city, a state, or a country). Thus, anin-vehicle GPS may provide the navigation system with the real-timelocation of the vehicle, and this location data may be used indetermining how certain types of buildings are rendered. That is, therendering of certain types of buildings may be dependent upon real-timegeographic location data that may be received from a GPS within thevehicle.

The stylized procedural modeling may be consistent, as illustrated inFIGS. 5 b and 5 c. For example, all buildings of the same type (e.g.,church) may be visualized in a similar way in a typical given city,area, state or country. Therefore, each of these non-landmark buildingsmay be visualized as a 3D icon that presents the most importantinformation to the driver (e.g., shape, height and type). FIG. 5 dillustrates another example of stylized procedural modeling of a carparking building.

Another feature of the stylized procedural modelling of the presentinvention may be decomposing an input irregular footprint into tractableparts. The tractable parts may be the basic units of a footprint from anarchitecture point of view. For example, a tractable part could be aconvex quadrilateral, which represents a basic room structure in 3D. Atractable part could also be a circle, which may represent a pillar in3D. FIGS. 6 a-d illustrate one embodiment of a method of the inventionfor decomposing an input irregular footprint into tractable parts.First, according to building attributes (e.g., building type) andgeometry complexity level, predefined procedural modelling rules may beapplied to tractable parts to derive stylized 3D building components.Then after individual 3D building components are generated from thecorresponding tractable part, they may be combined into one complete 3Dstructure for stylized visualization. Stylized procedural modeling maytake the 2D footprint along with building attributes as input and mayoutput a 3D building with stylized visualizations on-line. Decompositionmay be first applied to the 2D footprint (FIG. 6 a) to thereby arrive ata decomposition of the footprint (FIG. 6 b). The resultant tractableparts (FIG. 6 c) may be modeled separately. The final 3D building (FIG.6 d) may be the combination of all individual 3D components.

Yet another feature of the stylized procedural modelling of the presentinvention may be that the method is adaptive to accommodate real-timeperformance requirements of procedural modeling for large-scale scenes.The complexity level of resultant 3D buildings may be adjusted toachieve better run-time performance. FIGS. 7 a and 7 b are examples ofadaptive stylized procedural modelling that illustrate the adjustabilityof the complexity level of resultant 3D buildings. More particularly,FIGS. 7 a and 7 b are two buildings of the same type generated from thesame 2D footprint. The building of FIG. 7 a has more complicatedgeometric structures for the roof as compared to the flat roof in FIG. 7b.

The complexity can increase when the current rendering speed, which maybe expressed in frames per second (fps), is above the target number.Conversely, the complexity may decrease when the current rendering speeddoes not meet the speed requirement. A hierarchical set of proceduralmodelling rules (i.e., having different levels) may be predefined fortractable parts. Therefore, the geometric complexity of generatedbuildings may be controlled by changing the level for proceduralmodelling operations dynamically.

The present invention includes several novel features. First, theinvention provides a novel approach to performing stylized proceduralmodeling on-line based on the input of a 2D footprint and attributeinformation of the building. Second, the invention provides an enhanced“3D icon” -like approach to visualize non-landmark buildings. Third, theinvention provides a method of decomposing a 2D footprint into severaltractable parts and combining each modeling result into one complexmodel. Fourth, the invention provides an adaptive procedural modelingmethod in which the geometric or appearance complexity of generated 3Dbuildings may be controlled to meet the target performance of thehardware platform.

In FIG. 8 there is shown one embodiment of a 3D map renderingarrangement 10 of the present invention that may be associated with avehicle, such as an automobile. That is, arrangement 10 may be installedin-vehicle.

Arrangement 10 may include a source 12 of 3D map data, a 3D maprendering engine 14, and a user interface 16. 3D map data source 12 maybe in the form of a compact disc (CD) or other memory device.Alternatively, 3D map data may be wirelessly transmitted by a centraltransmitter (not shown) to a large number of vehicles that each has arespective 3D map rendering arrangement 10. Such wireless transmissionsmay be received by engine 14. 3D map data could include both 3D and 2Ddata as long as the data is used for 3D map visualization.

3D map data source 12 may also include a global positioning system (GPS)module (not shown) for determining the global location coordinates ofthe vehicle in real time. Based on the current location of the vehicle,corresponding 3D map data that is of interest to people within thevehicle is identified and provided to engine 14. At least some of the 3Dmap data may be photorealistic in visual style.

3D map rendering engine 14 may include a standard electronic processorthat converts the 3D map data from source 12 into image data. During thecourse of rendering, engine 14 may select certain 3D objects in the databased on criteria provided by the user and may render the selected 3Dobjects in highlighted or enhanced rendering style, as described above.In one embodiment, at least some of the highlighted image data may be invarious nonphotorealistic styles, such as cartoon-like rendering, pencilsketches, pen-and-ink illustrations, oil painting effects, and otherpainterly styles. The nonphotorealistic renderings may depict surfacesof objects and distinctive or well-known features of the objects.

User interface 16 may be disposed on a dashboard of a vehicle and mayinclude a display screen 18 and a control device 20. Display screen 18may include a processor and memory for controlling the information orcontent that is displayed on the screen or monitor. Generally, displayscreen 18 may present or depict 3D data received from engine 14.

Control device 20 may be in the form of a dial, knob, set ofpushbuttons, joystick, microphone, or any combination of the above. Auser may use control device 20 to provide feedback 22 to engine 14.Feedback 22 may instruct engine 14 to produce another set of image data(e.g., image data depicting another scene, object or set of objects).Alternatively, feedback 22 may instruct engine 14 to change the viewingangle at which a current set of image data is being viewed. The viewingangle may vary from an overhead bird's-eye view of the surroundings toan angle looking up at buildings, or at other landmarks, from a groundlevel or street level.

An embodiment of a method 900 of the present invention for displaying anavigation map is illustrated in FIG. 9. In a first step 902, a route ofa vehicle is determined. For example, the arrangement of FIG. 8 mayinclude a navigation system that automatically and continuously updatesan optimum path or route from a vehicle's current location to a desireddestination. A GPS or other location-determining device associated withthe arrangement of FIG. 8 may ascertain and continuously update thecurrent location of the vehicle, which may be expressed in globalcoordinates. The user inputs his desired destination into the system andthe system automatically determines the shortest and/or quickest routefrom the current location to the destination location along the streetsthat are available.

In a next step 904, a two-dimensional footprint of a building that isdisposed within a geographic area is received within the vehicle. Thegeographic area includes the route of the vehicle. For example, based onthe vehicle's route determined in step 902, map data associated with thegeographic area surrounding the route of the vehicle may be retrievedfrom a memory device, such as a CD. Alternatively, the map dataassociated with the geographic area surrounding the route of the vehiclemay be wirelessly received from a central repository of map data.Regardless of how it is received, the map data may include 2D datadescribing the shape and dimensions of the bases (i.e., 2D footprints)of the buildings within the geographic area surrounding the route of thevehicle.

Next, in step 906, attribute information associated with the building isreceived within the vehicle. For example, the map data described withreference to step 904 may include building attribute informationincluding the types and heights of each of the buildings within thegeographic area surrounding the route of the vehicle.

In a final step 908, a visual representation of the building is renderedbased upon the two-dimensional footprint and the attribute information.For example, a rendering of the building may have a footprint that issubstantially similar in shape to the footprint of the actual building.Further, the rendering may have a height relative to the footprintdimensions that is proportional to the height versus footprintdimensions of the actual building. Further still, the rendering mayinclude a color scheme and texturing that is designated for thatparticular type of building. For example, as described above with regardto FIGS. 5 b-c, all buildings of the type “church” in Berlin may berendered with the same greenish roofs and doors with cross-likedecorations. As another example, all banks in the United States may berendered with two white pillars to the left, and two white pillars tothe right of a front door, with a “$” symbol disposed above the door. Asyet another example, all primary-level schools disposed in theMidwestern states of the United States may be rendered in red brick witha school bell near the top of the building.

An embodiment of a method 1000 of the present invention for displaying anavigation map is illustrated in FIG. 10. In a first step 1002, a routeof a vehicle is determined. In a next step 1004, geographicalcoordinates of a location of the vehicle are received. For example, aGPS or other location-determining device associated with the arrangementof FIG. 8 may ascertain and continuously update the current location ofthe vehicle, which may be expressed in global coordinates.

Next, in step 1006, a geographic area in which the geographiccoordinates are disposed is determined. That is, a geographic areaincluding the geographic coordinates and having consistent, ormonolithic architecture for at least one certain type of building isdetermined. For example, as described above with respect to FIGS. 5 b-c,a geographic area in the form of the city of Berlin is identified ashaving churches with a common architecture including greenish roofs anddoors with cross-like decorations. As another example, a geographic areain the form of the United States may be identified as having banks withwhite pillars in the front of the building. As yet another example, ageographic area in the form of the Midwestern states of the UnitedStates may be identified as having primary-level schools built with redbricks.

In a next step 1008, data associated with buildings that are disposedwithin the geographic area is received. The geographic area includes theroute of the vehicle. The data includes building types, 3D shapes, andbuilding heights. For example, data associated with buildings in thegeographic area including the route of the vehicle may be retrieved froma memory device, such as a CD. Alternatively, the data associated withbuildings in the geographic area including the route of the vehicle maybe wirelessly received from a central repository of map data. Regardlessof how it is received, the data may include data describing the typesand heights of the buildings within the geographic area including theroute of the vehicle.

In a final step 1010, each of the buildings is rendered based upon thegeographic area in which the building is disposed, the building's type,and the building's height. For example, the color scheme and/ortexturing in which the buildings are rendered may depend upon the commonarchitectural style for certain types of buildings within the geographicarea. Further, the rendering may match the actual buildings' 3D shapesand heights such that the dimensions of the rendered buildings areproportional to the actual dimensions of the individual buildings. The2D footprint plus height could determine the rough 3D shape of thebuilding. For non-landmark buildings, the 3D shape/geometry is generatedby the inventive algorithm. The 3D shape/geometry is not included in thedata.

Yet another embodiment of a method 1100 of the present invention fordisplaying a navigation map is illustrated in FIG. 11. In a first step1102, a route of a vehicle is determined. In a next step 1104, atwo-dimensional footprint of a building that is disposed within ageographic area is received within the vehicle. The geographic areaincludes the route of the vehicle. Next, in step 1106, thetwo-dimensional footprint is decomposed into tractable parts. Forexample, the two-dimensional footprint shown in FIG. 6 a may bedecomposed into the three tractable parts indicated in FIG. 6 b. In oneembodiment, the tractable parts may be formed by adding bounding linesbetween corners of the footprint to thereby form quadrilateral parts, asis the case in FIG. 6 b.

In a next step 1108, each of the tractable parts is modeled separatelyin combination with a respective portion of the geometry informationassociated with each of the tractable parts. For example, each of thethree tractable parts of FIG. 6 b may be modeled separately incombination with a respective portion of the geometry information ofFIG. 6 c that is disposed directly above the respective tractable part.

In a final step 1110, a visual representation of the building isrendered based upon a combination of the modelings of each of thetractable parts. That is, the three separate modelings, each includingone of the three tractable parts of FIG. 6 b along with the respectiveportion of the building geometry of FIG. 6 c, may be combined to therebyrender a stylized 3D visual representation of the building, as depictedin FIG. 6 d.

While this invention has been described as having an exemplary design,the present invention may be further modified within the spirit andscope of this disclosure. This application is therefore intended tocover any variations, uses, or adaptations of the invention using itsgeneral principles.

What is claimed is:
 1. A method of displaying a navigation map,comprising the steps of: determining a route of a vehicle; receivingwithin the vehicle a two-dimensional footprint of a building that isdisposed within a geographic area, the geographic area including theroute of the vehicle; receiving attribute information associated withthe building, the attribute information being received within thevehicle; rendering a visual representation of the building based uponthe two-dimensional footprint and the attribute information; controllingthe geometric complexity and/or appearance complexity of the renderingof the building dependent upon a hardware platform within the vehicle.2. The method of claim 1 wherein the attribute information comprises thebuilding's type.
 3. The method of claim 2 wherein a color scheme of therendered building is dependent upon the building's type.
 4. The methodof claim 2 wherein texturing of the rendered building is dependent uponthe building's type.
 5. The method of claim 1 wherein the attributeinformation comprises the building's height.
 6. The method of claim 1comprising the further steps of: determining a target performance levelof the hardware platform within the vehicle; and controlling thegeometric complexity and/or appearance complexity of the rendering ofthe building in order to meet the target performance level.
 7. Themethod of claim 1 comprising the further steps of: decomposing thetwo-dimensional footprint into tractable parts; and modeling each of thetractable parts separately in combination with a respective portion ofthe geometry information associated with each of the tractable parts,wherein the rendering of the visual representation of the building isbased upon a combination of the modelings of each of the tractableparts.
 8. A method of displaying a navigation map, comprising the stepsof: determining a route of a vehicle; receiving geographical coordinatesof a location of the vehicle; determining a geographic area in which thegeographical coordinates are disposed; receiving data associated withbuildings that are disposed within the geographic area, the geographicarea including the route of the vehicle, the data including: buildingtypes; and building heights; and rendering each of the buildings basedupon: the geographic area in which the building is disposed; thebuilding's type; and the building's height.
 9. The method of claim 8wherein each of the buildings comprises a non-landmark building.
 10. Themethod of claim 8 wherein the color and texture in which each buildingis rendered is dependent upon the building's type.
 11. The method ofclaim 8 wherein buildings of the same type and of the same geographicarea are rendered in the same colors and same texture.
 12. The method ofclaim 8 wherein a color scheme and texturing of each of the renderedbuildings is dependent upon each of the buildings' type.
 13. The methodof claim 8 comprising the further steps of: determining a targetperformance level of a hardware platform within the vehicle; andcontrolling the geometric complexity and/or appearance complexity of therendering of each of the buildings in order to meet the targetperformance level.
 14. A method of displaying a navigation map,comprising the steps of: determining a route of a vehicle; receivingwithin the vehicle a two-dimensional footprint of a building that isdisposed within a geographic area, the geographic area including theroute of the vehicle; decomposing the two-dimensional footprint intotractable parts; modeling each of the tractable parts separately incombination with a respective portion of the geometry informationassociated with each of the tractable parts; and rendering a visualrepresentation of the building based upon a combination of the modelingsof each of the tractable parts.
 15. The method of claim 14 wherein acolor scheme of the rendered building is dependent upon the building'stype.
 16. The method of claim 15 wherein texturing of the renderedbuilding is dependent upon the building's type.
 17. The method of claim14 comprising the further steps of: determining a target performancelevel of a hardware platform within the vehicle; and controlling thegeometric complexity of the rendering of the building in order to meetthe target performance level.
 18. The method of claim 14 comprising thefurther steps of: determining a target performance level of a hardwareplatform within the vehicle; and controlling the appearance complexityof the rendering of the building in order to meet the target performancelevel.
 19. The method of claim 14 wherein the visual representation ofthe building is rendered based upon: the geographic area in which thebuilding is disposed; the building's type; and the building's height.20. The method of claim 19 wherein all the visual representations ofsaid buildings of a same said type are rendered with a same color schemeand with same texturing.